Keith Dysart wrote:
. . .
Notice a key point about this description. It is
completely in terms of charge. There is not a single
mention of EM waves, travelling or otherwise.

Now we expand the experiment by placing a pulse
generator at each end of the line and triggering
them to each generate a 50V one second pulse at
the same time. So after one second a pulse has
completely entered each end of the line and these
pulse are racing towards each other at the speed
of light (in the line). In another second these
pulses will collide at the middle of the line.

What will happen? Recall one of the basics about
charge: like charge repel. So it is no surprise
that these two pulses of charge bounce off each
and head back from where they came. At the center
of the line, for one second the voltage is 100 V
(50 V from each pulse), while the current is
always zero. No charge crossed the mid-point. No
energy crossed the mid-point (how could it if
the current is always zero (i.e. no charge
moves) at the mid-point.

. . .

That's an interesting and compelling argument. With the conditions you
describe, I don't see how it would be possible to tell whether the waves
reflected from each other or simply passed by without interacting.

But suppose we launch waves of different shapes from the two directions,
say a triangular wave and a rectangular one. Or perhaps make them
asymmetrical in some fashion. It seems to me that then we should be able
to tell which of the two possibilities happened. Being different, you
could argue that the reflection wouldn't be complete. But shouldn't we
expect some distortion of any part of a pulse that was acted upon by the
other?

I'll put my money on each of the waves arriving at the opposite end
unchanged. What do you predict will happen?

Roy Lewallen, W7EL